Refactor profiler

- move the save method to an inner class
- don't use a timer, use a blocking queue instead
- add a format enum (in anticipation of adding a json output format)
- update the test to use an in memory buffer, and avoid FoundationTestCase

Compared to the original https://github.com/bazelbuild/bazel/commit/15b8c259db111012b4642287172cb4d1d82151f3, it contains these changes:
- Make it so we don't create a queue if we are not going to write any
  data! The queue is now owned by the writer, and if there is no writer, there
  is no queue.

  This was causing a memory regression because slowest task profiling is
  enabled by default, in which case the profiler is started with no output
  file. In that case, there's no thread that is emptying the queue, but the
  queue was still created by default.

- add additional tests for slowest task and histogram handling; these also
  provide coverage for the case where the profiler is started without an output
  stream
- move all the writer thread handling into the inner class
- make writer access thread-safe
- add a bunch of documentation

PiperOrigin-RevId: 200212978

1 files changed, 12 insertions, 3 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/profiler/ProfilerChartTest.java b/src/test/java/com/google/devtools/build/lib/profiler/ProfilerChartTest.java
index 105afb0535..6b3bd519ad 100644
--- a/src/test/java/com/google/devtools/build/lib/profiler/ProfilerChartTest.java
+++ b/src/test/java/com/google/devtools/build/lib/profiler/ProfilerChartTest.java
@@ -35,6 +35,7 @@ import com.google.devtools.build.lib.testutil.Scratch;
 import com.google.devtools.build.lib.testutil.Suite;
 import com.google.devtools.build.lib.testutil.TestSpec;
 import com.google.devtools.build.lib.vfs.Path;
+import java.io.InputStream;
 import java.util.List;
 import java.util.Locale;
 import org.junit.Test;
@@ -248,8 +249,14 @@ public class ProfilerChartTest extends FoundationTestCase {
     Path cacheDir = scratch.dir("/tmp");
     Path cacheFile = cacheDir.getRelative("profile1.dat");
     Profiler profiler = Profiler.instance();
-    profiler.start(ProfiledTaskKinds.ALL, cacheFile.getOutputStream(), "basic test", false,
-        BlazeClock.instance(), BlazeClock.instance().nanoTime());
+    profiler.start(
+        ProfiledTaskKinds.ALL,
+        cacheFile.getOutputStream(),
+        Profiler.Format.BINARY_BAZEL_FORMAT,
+        "basic test",
+        false,
+        BlazeClock.instance(),
+        BlazeClock.instance().nanoTime());
 
     // Write from multiple threads to generate multiple rows in the chart.
     for (int i = 0; i < noOfRows; i++) {
@@ -259,7 +266,9 @@ public class ProfilerChartTest extends FoundationTestCase {
     }
 
     profiler.stop();
-    return ProfileInfo.loadProfile(cacheFile);
+    try (InputStream in = cacheFile.getInputStream()) {
+      return ProfileInfo.loadProfile(in);
+    }
   }
 
   private void task(final Profiler profiler, ProfilerTask task, String name) {